Connection element and spine stabilization system

ABSTRACT

The present invention relates to a connection element for a spine stabilization system which comprises a first end for fixing to a first bone fixation device, a second end for fixing to a second bone fixation device and an intermediate portion arranged or formed between the two ends and defining a longitudinal axis. At least one of the two ends takes the form of a coupling element for fixing the connection element to a bone fixation device in at least one defined orientation relative to the longitudinal axis. The coupling element has a shape other than a circular cylinder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of commonly-owned co-pending U.S.application Ser. No. 14/480,745 filed on Sep. 9, 2014, which claims thebenefit of German patent application number 10 2013 110 173.9 filed onSep. 16, 2013, each of which is incorporated by reference herein in itsentirety and for all purposes.

FIELD OF THE INVENTION

The present invention relates to connection elements for spinestabilization systems generally, and more specifically to a connectionelement for a spine stabilization system with a first end for fixing toa first bone fixation device, a second end for fixing to a second bonefixation device and an intermediate portion arranged or formed betweenthe two ends and defining a longitudinal axis.

The present invention further relates to spine stabilization systemsgenerally, and more specifically to a spine stabilization systemcomprising at least one first bone fixation device, at least one secondbone fixation device and at least one connection element, which at leastone connection element comprises a first end for fixing to the at leastone first bone fixation device, a second end for fixing to the at leastone second bone fixation device and an intermediate portion arranged orformed between the two ends and defining a longitudinal axis.

BACKGROUND OF THE INVENTION

Connection elements and spine stabilization systems of theabove-described type are known for example from EP 1 658 815 B1. Theconnection elements described in this European Patent comprise resilientelements and have first and second ends, which are each circularcylindrical in form and the longitudinal axes of which coincide. Theymay be fixed in clamped manner in corresponding bone fixation devicereceptacles.

A disadvantage of the known connection elements is, however, that theintermediate portion can only be oriented in a defined way with veryconsiderable effort.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a connection element for a spinestabilization system comprises a first end for fixing to a first bonefixation device, a second end for fixing to a second bone fixationdevice and an intermediate portion arranged or formed between the twoends and defining a longitudinal axis. At least one of the two endstakes the form of a coupling element for fixing the connection elementto a bone fixation device in at least one defined orientation relativeto the longitudinal axis. The coupling element has a shape other than acircular cylinder.

In a second aspect of the invention, a spine stabilization systemcomprises at least one first bone fixation device, at least one secondbone fixation device and at least one connection element. Said at leastone connection element comprises a first end for fixing to the at leastone first bone fixation device, a second end for fixing to the at leastone second bone fixation device and an intermediate portion arranged orformed between the two ends and defining a longitudinal axis. At leastone of the two ends takes the form of a coupling element for fixing theconnection element to a bone fixation device in at least one definedorientation relative to the longitudinal axis and wherein the couplingelement has a shape other than a circular cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary and the following description may be betterunderstood in conjunction with the drawing figures, of which:

FIG. 1: is a schematic perspective overall view of a spine stabilizationsystem fixed to a spinal column;

FIG. 2: is a view of a first exemplary embodiment of a connectionelement, fixed to two bone screws;

FIG. 3: is an exploded representation of the arrangement of FIG. 2;

FIG. 4: is partially sectional view of the arrangement in FIG. 2 alongline 4-4;

FIG. 5: is a view in the direction of arrow A in FIG. 4;

FIG. 6: is a view in the direction of arrow B in FIG. 5;

FIG. 7: is a side view of the connection element of FIG. 3;

FIG. 8: is a view of the connection element of FIG. 7 in the directionof arrow C;

FIG. 9: is a view of the connection element of FIG. 7 in the directionof arrow D;

FIG. 10: is a schematic perspective view of a second exemplaryembodiment of a connection element in the process of being fixed to twobone screws;

FIG. 11: is a view of the arrangement of FIG. 10 in the direction ofarrow E;

FIG. 12: is a view of the arrangement of FIG. 11 in the direction ofarrow F;

FIG. 13: is a side view of the second exemplary embodiment of aconnection element;

FIG. 14: is a view of the connection element of FIG. 13 in the directionof arrow G;

FIG. 15: is a view of the connection element of FIG. 13 in the directionof arrow H;

FIG. 16: is a schematic perspective view of a third exemplary embodimentof a connection element in the process of being fixed to two bonescrews;

FIG. 17: is a view of the arrangement of FIG. 16 in the direction ofarrow I;

FIG. 18: is a side view of the connection element of FIG. 17;

FIG. 19: is a view of the connection element of FIG. 18 in the directionof arrow J;

FIG. 20: is a schematic perspective view of a fourth exemplaryembodiment of a connection element in the process of being fixed to abone screw with a further rod-shaped connection element;

FIG. 21: is an exploded representation of the arrangement of FIG. 20;

FIG. 22: is a view of the arrangement of FIG. 21 in the direction ofarrow K;

FIG. 23: is a view of the two connection elements in FIG. 22 in thedirection of arrow L;

FIG. 24: is a view of the connection element of FIG. 25 in the directionof arrow M;

FIG. 25: is a side view of the connection element of FIG. 23;

FIG. 26: is a schematic perspective view of a fifth exemplary embodimentof a connection element in the process of being fixed to a bone screw;

FIG. 27: is an exploded representation of the arrangement of FIG. 26;

FIG. 28: is a partially sectional view of the arrangement of FIG. 27along line 28-28;

FIG. 29: is a view of the connection element of FIG. 30 in the directionof arrow N;

FIG. 30: is a side view of the connection element of FIG. 27;

FIG. 31: is a schematic perspective view of a sixth exemplary embodimentof a connection element in the process of being fixed to a bone screw;

FIG. 32: is a partially sectional view along line 32-32 of FIG. 31;

FIG. 33: is a view of the connection element of FIG. 34 in the directionof arrow O;

FIG. 34: is a side view of the connection element of FIG. 32;

FIG. 35: is a schematic perspective view of a seventh exemplaryembodiment of a connection element in the process of being fixed to twobone screws;

FIG. 36: is a partially sectional view along line 36-36 in FIG. 35;

FIG. 37: is a view of the connection element of FIG. 38 in the directionof arrow P;

FIG. 38: is a side view of the connection element of FIG. 35;

FIG. 39: is a perspective view of an eighth exemplary embodiment of aconnection element;

FIG. 40: is a view of the connection element of FIG. 39 in the directionof arrow Q;

FIG. 41: is a schematic perspective view of a ninth exemplary embodimentof a connection element in the process of being fixed to two bonescrews;

FIG. 42: is a view of the arrangement of FIG. 41 in the direction ofarrow R;

FIG. 43: is a view of the connection element of FIG. 44 in the directionof arrow T;

FIG. 44: is a side view of the connection element of FIG. 41;

FIG. 45: is a view of the connection element of FIG. 44 in the directionof arrow S;

FIG. 46: is a perspective view of a tenth exemplary embodiment of aconnection element;

FIG. 47: is a view of the connection element of FIG. 46 in the directionof arrow U;

FIG. 48: is a view of the connection element of FIG. 47 in the directionof arrow V;

FIG. 49: is a schematic perspective view of an eleventh and a twelfthexemplary embodiment of a connection element in the process of beingjointly fixed to a single bone screw;

FIG. 50: is an exploded representation of the arrangement of FIG. 49;

FIG. 51: is a partially sectional view of the arrangement of FIG. 49along line 51-51;

FIG. 52: is a view of the two connection elements of FIG. 53 in thedirection of arrow W;

FIG. 53: is a partially sectional side view of the coupled-togetherconnection elements of FIG. 49;

FIG. 54: is a schematic perspective view of a thirteenth and afourteenth exemplary embodiment of a connection element in the processof being jointly fixed to a single bone screw;

FIG. 55: is a partially sectional view along line 55-55 in FIG. 54;

FIG. 56: is a partially sectional side view of the two coupled-togetherconnection elements of FIG. 55;

FIG. 57: is a schematic perspective view of a fifteenth and a sixteenthexemplary embodiment of a connection element in the process of beingjointly fixed to a single bone screw;

FIG. 58: is a partially sectional view of the arrangement of FIG. 57along line 58-58;

FIG. 59: is an exploded representation of the arrangement of FIG. 57;

FIG. 60: is a plan view of the coupled-together connection elements ofFIG. 57;

FIG. 61: is a sectional view along line 61-61 in FIG. 60;

FIG. 62: is a schematic perspective view of a seventeenth exemplaryembodiment of a connection element which is fixed to a bone screw with afurther rod-shaped connection element;

FIG. 63: is a partially sectional view of the arrangement of FIG. 62along line 63-63;

FIG. 64: is a perspective view of the connection element of FIG. 63 fromabove;

FIG. 65: is a perspective view of the connection element of FIG. 64 frombelow;

FIG. 66: is a view of the connection element of FIG. 67 in the directionof arrow Y; and

FIG. 67: is a view of the connection element of FIG. 66 in the directionof arrow X.

DETAILED DESCRIPTION

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

The present invention relates to a connection element for a spinestabilization system with a first end for fixing to a first bonefixation device, a second end for fixing to a second bone fixationdevice and an intermediate portion arranged or formed between the twoends and defining a longitudinal axis, wherein at least one of the twoends takes the form of a coupling element for fixing the connectionelement to a bone fixation device in at least one defined orientationrelative to the longitudinal axis and wherein the coupling element has ashape other than a circular cylinder.

This particular configuration makes it possible for an operator simplyand reliably to implant the connection element with a definedorientation, i.e. in particular to fix it with a defined orientation tothe bone fixation devices. Ends in the form of circular cylinders, asprovided in the case of the connection elements known from EP 1 658 815B1, do not define any preferential direction due to their rotationallysymmetrical shape. Although they do allow any desired orientation of theconnection element and thus orientation of the intermediate portionrelative to the longitudinal axis thereof, this may actually bedisadvantageous if, for example, the intermediate portion likewisedefines a preferential direction, which is possible in particular in thecase of flexible or partially flexible intermediate portions, and istherefore intended to be oriented in defined manner relative to the bonefixation devices. It is precisely this problem that is solved by theparticular configuration of at least one of the two ends, or indeed ofboth ends, in the form of a coupling element having a shape other than acircular cylinder. In particular, the coupling element is configured bydefinition, unlike a circular cylinder, to be not fully rotationallysymmetrical, such that even in the case of a connection elementreceptacle which is provided on a bone fixation device and may beconfigured to be rotationally symmetrical or substantially rotationallysymmetrical, a defined orientation of the connection element and thus ofthe intermediate portion thereof relative to the longitudinal axis ispossible, and that without an operator having to make particularly greatefforts. Preferably, precisely one defined orientation is possible, dueto a shaping of the coupling element.

The two ends are favourably configured in the form of a coupling elementwhich has a shape other than a circular cylinder. In this way, anoptimal connection with two bone fixation devices may be achieved.

The connection element may be simply produced if the coupling element ismade in one piece. For example it may be formed by machining or producedby casting.

To improve the stability of the connection element, it is advantageousfor it to be in one piece.

So that the connection element can be fixed simply and reliably to atleast one bone fixation device with a defined orientation relativethereto, it is favourable for the coupling element to comprise acoupling element main body and at least one coupling member arranged orformed on the coupling element main body. The at least one couplingmember may serve in particular to co-operate with a corresponding parton the bone fixation device or indeed with a further coupling member ona further connection element, for example to be able in this way tolengthen the connection element if required. In particular, the at leastone coupling member may be configured to be brought into positiveengagement with correspondingly provided further coupling members onother connection elements or on a bone fixation device.

Preferably, the at least one coupling member extends in a couplingmember direction which extends parallel to or transversely of thelongitudinal axis. Depending on how in particular a connection elementreceptacle is configured on a bone fixation device, an optimalconnection with a bone fixation device can be achieved by correspondingpredetermination of the coupling member direction, in particularrotation or axial displacement relative to the bone fixation device mayin this way be simply and reliably prevented.

The connection element may be simply constructed if the coupling elementmain body is given the form of a straight or oblique general cylinderand if a cylinder longitudinal axis defined by the cylinder extendstransversely of the longitudinal axis. A general cylinder has the samecross-sectional area in mutually parallel section planes. Thecross-sectional area may have any desired shape but deviates accordingto the invention from a circle in order to avoid undefined orientationof the intermediate portion relative to the bone fixation devices.Alternatively, a cylinder longitudinal axis of the general cylinder mayalso extend parallel to the longitudinal axis of the connection element.

It is favourable for the coupling element main body to have across-sectional area which is circular, quadrangular or in the form of amultiple lobe member. In particular, the cross-sectional area may berectangular or square. Such basic shapes are simple to produce and allowa defined orientation of the connection element relative to a bonefixation device.

Advantageously the at least one coupling member takes the form of acoupling projection or a coupling receptacle. It may thus co-operate indesired manner with corresponding recesses and projections.

Preferably the coupling projection is crowned, spherical, cylindrical,conical, cuboidal or takes the form of a combination of one or more ofthese shapes. In particular, the coupling projection may be conformed toa connection element receptacle of a bone fixation device, so as inparticular to allow interlocking engagement.

According to a further preferred embodiment of the invention, provisionmay be made for the coupling receptacle to be hollow-crowned,hollow-spherical, hollow-cylindrical, cuboidal, in the form of a throughopening in the coupling element main body or in the form of acombination of one or more of these shapes. In particular, a couplingreceptacle shaped in this way may co-operate with a correspondinglyshaped coupling projection of a further connection element, in order forexample in this way to couple two ends of two connection elementstogether and fix them jointly to a bone fixation device.

The coupling receptacle may favourably take the form of a set-backportion or a groove. These may extend parallel to or transversely of thelongitudinal axis.

It is advantageous for the coupling receptacle to be open in a directiontransversely of and/or parallel to the longitudinal axis. Thus, it may,in cooperation with a further coupling member, prevent relative motionof the connection element relative to a bone fixation device parallel toand/or transversely of the longitudinal axis.

The connection element favourably has two, three or more couplingmembers. It is also possible for there to be in particular four, five orsix coupling members. In particular, the coupling members have couplingmember longitudinal axes oriented in different directions, in order inthis way to limit movement of the connection element relative to a bonefixation device or a further connection element in different directions.

The connection element may be simply constructed if the coupling elementhas two coupling members arranged or formed in mirror-symmetrical mannerrelative to a mirror plane containing the longitudinal axis. These mayfor example be set-back portions or grooves extending parallel to oneanother.

It may moreover be favourable for the coupling element to bemirror-symmetrical relative to a mirror plane containing thelongitudinal axis. It is thus possible, depending on the shape of thecoupling element, to predetermine for example one, two or four definedorientations of the connection element relative to a bone fixationdevice.

The connection element may be particularly simply constructed if it ismirror-symmetrical relative to a mirror plane containing thelongitudinal axis.

To fix the connection element in a particularly space-saving manner andoptionally with a further connection element jointly in a connectionelement receptacle of a fixation device, it is advantageous for a centreof gravity of the coupling element to be spaced from the longitudinalaxis.

Introduction of the connection element into the body of a patient, inparticular in minimally invasive operations, may be improved and therisk of injury minimized if an end face of the coupling element facingaway from the intermediate portion is inclined relative to thelongitudinal axis or rounded.

Such an end face may be simply produced if an end face plane defined bythe end face and the longitudinal axis form an end face angle ofinclination which lies within a range of around 30° to 90°, preferablyin a range of around 45° to 75°.

It is advantageous for the coupling element main body to include aportion of a circular cylinder, which has a circular cylinder axisextending transversely of the longitudinal axis. For example, thecoupling element main body may engage in a corresponding recess in sucha way that movement parallel to the longitudinal axis of the connectionelement relative to a bone fixation device or a further connectionelement may be simply and reliably limited.

It may furthermore be favourable for the coupling element main body tohave a planar surface portion which defines a plane which extendsparallel to or transversely of the longitudinal axis. In particular, asurface portion which defines a plane extending parallel to thelongitudinal axis allows a flat contact for example with a fixingelement for fixing the connection element to the bone fixation device.Furthermore, two ends of two connection elements may thus also abutflatly against one another.

According to a further preferred embodiment of the invention, provisionmay be made for the coupling element to comprise a connection elementcontact face for application against a further connection element. Inparticular, the connection element contact face may be configured toabut an end of the further connection element. Such a configurationenables particularly good and reliable coupling with a furtherconnection element.

The connection element contact face preferably takes the form at leastin part of a hollow-cylindrical wall surface. Such a configuration makesit possible in particular to receive an end of a further connectionelement in the form of a circular cylinder and extending in thedirection of the longitudinal axis or parallel thereto.

It is favourable for the connection element contact face to take theform at least in part of a planar contact face portion. Such aconnection element contact face is simple to produce and apply against acorresponding planar connection element contact face.

According to a further preferred embodiment of the invention, provisionmay be made for the coupling element main body to comprise two, three ormore coupling element main body side faces which are planar or concavelycurved away from the coupling element main body and inclined relative toone another. In particular, coupling element main body side facesinclined relative to one another, even if they are planar, may produce aconcave shape facing away from the coupling element main body. Such acoupling element main body may in particular co-operate with acorresponding convex side face of a bone fixation device.

Production of the connection element may be further simplified ifmutually adjacent planar coupling element main body side faces form anobtuse angle between them.

It is favourable for the intermediate portion to be a winding leafspring element in the form of a strip and to comprise at least onerecess open laterally in a recess direction transverse to a longitudinalaxis defined by the intermediate portion. Such an intermediate portionmakes it possible to set a defined resilience of the connection elementand a defined anisotropy of the resilience in the circumferentialdirection relative to the longitudinal axis. Furthermore, the connectionelement with the recesses may be simply and reliably handled, forexample with a correspondingly shaped holding instrument. In addition,blocking elements may also be temporarily inserted into the recesses, inorder to limit the resilience of the connection element temporarilycompletely or in part, in particular during implantation.

According to a further preferred embodiment of the invention, provisionmay be made for the coupling element to define at least one preferentialdirection transverse to the longitudinal axis and for the preferentialdirection and the recess direction to form an orientation angle in arange from 0° to 180°. The orientation angle preferably lies in a rangefrom 0° to 90°. As a result of this configuration of the couplingelement, an orientation of the connection element may be specifiedrelative to the longitudinal axis and thus also an orientation of therecess direction for example relative to the part of the bone fixationdevice on which the connection element receptacle is formed to receiveone end of the connection element.

The coupling element preferably defines two or more preferentialdirections. This allows an operator to arrange the connection element indifferent but defined orientations relative to the bone fixation device.

It is advantageous for a preferential angle between two preferentialdirections of the coupling element to correspond to an angle 180°/n,wherein n is the number of preferential directions defined overall bythe coupling member. If for example the coupling element defines twopreferential directions, the preferential angle amounts in particular to90°.

The connection element is advantageously made from a metallic materialor a plastics material. The materials are preferably biocompatible andhave the stability required for the application.

It is favourable for the metallic material to be or contain titanium, atitanium alloy or a cobalt-chromium alloy. Such materials are extremelysuitable as implant materials.

It is moreover advantageous for the plastics material to be or containpolyetherether ketone or carbon fibre reinforced polyetherether ketone.Such a plastics material is likewise biocompatible and has the stabilityrequired for the application.

The present invention further relates to a spine stabilization systemcomprising at least one first bone fixation device, at least one secondbone fixation device and at least one connection element, which at leastone connection element comprises a first end for fixing to the at leastone first bone fixation device, a second end for fixing to the at leastone second bone fixation device and an intermediate portion arranged orformed between the two ends and defining a longitudinal axis, wherein atleast one of the two ends takes the form of a coupling element forfixing the connection element to a bone fixation device in at least onedefined orientation relative to the longitudinal axis and wherein thecoupling element has a shape other than a circular cylinder.

Such spine stabilization systems having any one of the above-describedconnection elements then likewise have the advantages described herein.

It is favourable for the at least one first and/or the at least secondbone fixation devices to take the form of pedicle screws. In particular,the pedicle screws may take the form of polyaxial pedicle screws.Pedicle screws are in particular designed to be fixed to the pedicles ofvertebrae. If connection elements are fixed to the pedicle screws, themobility of a patient's spinal column may be wholly or partiallyrestricted in a defined manner.

It is moreover favourable for the at least one first and/or the at leastone second bone fixation device to have a fixing part and a holding partand for the holding part to have a connection element receptacle forreceiving at least one end of a connection element. The holding part mayoptionally be connected movably or immovably with the fixing part. Theholding part is preferably fixable in an implantation position relativeto the fixing part. This allows the holding part first of all to beoriented in the desired manner relative to the fixing part and thenfixed, for example with simultaneous fixing of the connection element inthe connection element receptacle.

A connection element receptacle may be formed in a particularly simplemanner if the holding part has two wall portions arranged symmetricallyto one another and laterally defining the connection element receptacle.Overall, a holding part which is fork-shaped may be formed in this way.It may also be stated that the connection element receptacle is formedby a slot in the holding part.

It is favourable for the at least one first and/or the at least onesecond bone fixation device to comprise a fixing screw with an externalthread and for the connection element receptacle to comprise an internalthread corresponding to the external thread. The fixing screw allowssimple fixing of an end of a connection element inserted into theconnection element receptacle temporarily or permanently to the first orsecond bone fixation device.

It is moreover advantageous for the coupling element main body to have aplanar clamping surface portion for a distal end of the fixing screw,which clamping surface portion defines a plane extending parallel orsubstantially parallel to the longitudinal axis. It is thus inparticular possible to clamp the clamping surface portion flatly with adistal end of the fixing screw.

The intermediate portion is preferably at least partially flexible. Withsuch an intermediate portion a defined mobility of the spinestabilization system may be preset. It is favourable for theintermediate portion to predetermine an anisotropic flexibility. In thisway, for example, flexion and extension in a patient's median plane maybe partially enabled, but not sideways bending of the spinal column.

According to a further preferred embodiment of the invention, provisionmay be made for the spine stabilization system to comprise twoconnection elements, which have mutually corresponding coupling elementswhich may be fixed jointly in a connection element receptacle of the atleast one first and/or the at least one second bone fixation device.This allows a particularly compact structure of the spine stabilizationsystem to be achieved. In particular, connection elements may in thisway be simply extended.

In particular, it is also possible to use only short connectionelements, which are of a length which specifically allows connectionbetween two bone fixation devices. It is for example moreover possible,with a single fixing screw, to fix not only one connection element inclamped manner to the bone fixation device, but also two connectionelements to a single bone fixation device.

It is advantageous for the coupling elements of the two connectionelements to have mutually corresponding coupling members, which, in acoupling position in which the two coupling elements are held jointly ina connection element receptacle of the at least one first and/or of theat least one second bone fixation device, co-operate in force- and/orpositive-locking manner or are in engagement with one another. Thecoupling members allow direct, in particular a positive-locking couplingbetween the two connection elements, and not just between the connectionelements and bone fixation device.

FIG. 1 is a schematic representation of a spine stabilization system 10comprising a total of four bone fixation devices 12 and two connectionelements 14. The bone fixation devices 12 take the form of bone screws16. FIGS. 1 to 6 show “polyaxial” bone screws 16, by way of example.

The bone screws 16 are screwed into the pedicles 18 of vertebrae 20 of aspinal column 22. For stabilization thereof, in each case one bone screw16 is screwed for example into pedicles 18 of adjacent vertebrae 20,said bone screws then being coupled together via a connection element14.

The polyaxial bone screws 16 comprise a fixing part 24 and a holdingpart 26. The fixing part 24 comprises a shank defining a longitudinalaxis 28 and having an external thread 32 for screwing into bone. Aproximal end of the shank 30 takes the form of a spherical head 34, onwhich the holding part 26 is movably mounted. The holding part 26 issubstantially in the form of a sleeve and has a hollow-spherical seat 36on the distal side for the head 34, such that the holding part 26 ispivotable in a mounted position about a centre point of the head 34relative to the fixing part 24. Starting from its proximal end 38, theholding part 26 comprises two notches 40 diametrically opposite oneanother relative to the longitudinal axis 28, so as to form two wallportions 44 arranged symmetrically relative to one another and relativeto the longitudinal axis 28 and laterally defining a connection elementreceptacle 42. Starting from the end 38, an internal thread 46 is formedon the holding part 26 in the region of the wall portions 44, whichinternal thread corresponds to an external thread 48 on a fixing screw50.

In addition, the holding part 26 comprises a clamping member 52 in theform of an insert 54. This has a hollow dome-shaped distal end 56, whichmay be brought into contact with the head 34. A proximal endsubstantially takes the form of a half cylinder sleeve 58, the cylindersleeve longitudinal axis 60 of which extends transversely of a holdingpart longitudinal axis 62. The cylinder sleeve 58 defines ahollow-cylindrical contact surface 64 for in particular a first end 66,in the form of a cylindrical rod, of the connection element 14.

In addition, the insert 54 has a through opening extending coaxially tothe holding part longitudinal axis 62 in the form of a bore 68.

The first end 66 may, as shown schematically in FIG. 4, be inserted intothe connection element receptacle 42 defined on the distal side by thecontact surface 64 and secured in clamped manner with the fixing screw50. At the same time, the holding part 26 is fixed in clamped mannerrelative to the fixing part 24 in a desired implantation position, inthat the clamping force introduced by means of the fixing screw 50 istransferred via the first end 66 to the insert 54, which in turn presseson the head 34.

The connection element 14 comprises the first end 66 and a second end 70and an at least partially flexible intermediate portion 74 arranged orformed therebetween and defining a longitudinal axis 72. Saidintermediate portion takes the form of a winding leaf spring element 76in the form of a strip. In addition, it comprises a total of fiverecesses 78 and 80 which are laterally open transversely of thelongitudinal axis 72 in a recess direction 82. The three recesses 80 areopen in opposing directions relative to the recesses 78. Due to theconfiguration as a leaf spring element 76, the intermediate portion 74and thus the connection element 14 are resilient in a defined manner.

A resilience of the intermediate portion 74 may additionally optionallybe varied by one or more stiffness modifiers 84. These may for examplebe arranged or configured in the form of short projections 86 in theform of strips on one or both surfaces 88 and 90 respectively of theleaf spring element 76. Preferably, they are in one piece with the leafspring element 76. Further examples of the configuration of stiffnessmodifiers 84 are known from DE 20 2010 008 865 U1.

The second end 70 of the connection element 14 takes the form of acoupling element 92 for fixing the connection element 14 to the bonefixation device 12 in at least one defined orientation relative to thelongitudinal axis 72. It has a shape other than a circular cylinder. Itis moreover of one-piece configuration, as is the connection element 14overall.

The coupling element 92 has a coupling element main body 94 and a totalof four coupling members 96 and 98. The coupling members 96, which takethe form of coupling projections 102 facing convexly away from thecoupling element main body 94, extend in a coupling member direction104, which extends transversely of the longitudinal axis 72. Thecoupling members 98 take the form of set-back portions 100 on thecuboidal coupling element main body 94 and define a coupling memberdirection 106 which extends parallel to the longitudinal axis 72.

Furthermore, an end face 108 of the coupling element 92 facing away fromthe intermediate portion 74 is inclined relative to the longitudinalaxis 72. The end face 108 defines an end face plane 110, which forms anend face angle of inclination 112 with the longitudinal axis 72 whichpreferably lies in a range from around 30° to around 90°. In the case ofthe connection element 14 illustrated schematically in FIGS. 1 to 9, theend face angle of inclination 112 amounts to around 60°.

The side faces 114 facing away from the coupling element main body 94and defined by the coupling members 96 together form a portion of acircular cylinder, the longitudinal axis of which defines a preferentialdirection 116 of the coupling element 92. This extends transversely ofthe longitudinal axis 72. A diameter defined by the coupling members 96is conformed to an internal diameter of the internal thread 46, suchthat the coupling element 92 may be fixed to the bone screw 16 indefined orientation relative to the longitudinal axis 72.

A centre of gravity of the coupling element 92 is spaced from thelongitudinal axis 72.

A top 118 of the coupling element main body 94 defines a planar surfaceportion 120, which defines a plane extending parallel to thelongitudinal axis 72. The surface portion 120 forms a clamping surfaceportion 122 for a distal end 124 of the fixing screw 50. In this way, toclamp the coupling element 92 in the connection element receptacle 42the end 124 may be pressed substantially flatly against the clampingface portion 122.

The set-back portions 100 are arranged and dimensioned such that theyabut edges 126 of the insert 54 extending parallel to the longitudinalaxis 72 and facing in the proximal direction.

The connection element 14 defines a preferential direction 116, and maythus be fixed precisely in a defined manner in the connection elementreceptacle 42. By the coupling members 96 the connection element 14 isadditionally secured parallel to the longitudinal axis 72 relative tothe bone screw 16, and thus cannot be moved parallel to the longitudinalaxis 72 relative to the bone screw 16 even when the fixing screw 50needs to be loosened a little. Rotation of the connection element 14about the longitudinal axis 72 relative to the bone screw 16 is likewisenot possible.

Further exemplary embodiments of connection elements will be describedin greater detail below, these differing substantially in theconfiguration of their coupling elements. Identical or comparable partsand elements are therefore designated with the same reference signs.

FIGS. 10 to 15 are schematic representations of a second exemplaryembodiment of a connection element denoted overall with reference sign14 a. The difference in the construction of the connection element 14 isthe shape of the coupling element 92.

This likewise has a cuboidal coupling element main body 94, away fromwhich two coupling members 96 extend laterally transversely of thelongitudinal axis 72. An end face 108 facing away from the intermediateportion 74 is rounded and forms together with the coupling members 96 apart of a cylindrical disc which comprises a cylindrical side face 114.A diameter of the coupling element 92 defined by the side face 114corresponds to an internal diameter of the internal thread 46, such thatthe coupling element 92 may be inserted into the connection elementreceptacle 42 for axial securing of the connection element 14 a in thedirection of the longitudinal axis 72 relative to the bone screw 16.

In addition, two further coupling members 98 extending parallel to thelongitudinal axis 72 are formed on the coupling element main body 94 inthe form of set-back portions 100. When the second end 70 has beeninserted into the connection element receptacle 42, these abut the edges126 of the insert 54.

The coupling element 92 defines a preferential direction 116 whichextends transversely of the longitudinal axis 72. The top 118 of thecoupling element 92 forms a planar clamping surface portion 122 for thedistal end 124 of the clamping screw 50.

Because of its configuration, the connection element 14 a may beoriented both parallel to the longitudinal axis 72 and in thecircumferential direction thereof in a defined manner relative to thebone screw 16.

FIGS. 16 to 19 are schematic representations of a third exemplaryembodiment of a connection element and are designated overall with thereference sign 14 b. It differs from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element 92 has a cuboidal coupling element main body 94,the top 118 of which defines a planar clamping surface portion 122. Anend face 118 facing away from the intermediate portion 74 is likewiseplanar and extends transversely of the longitudinal axis 72.

Two coupling members 96 projecting laterally, i.e. transversely of thelongitudinal axis 72 are formed on the coupling element main body 94, asare two coupling members 98 extending parallel to the longitudinal axis72. The coupling members 98 are formed in the bottom 128 of the couplingelement main body 94 in the form of set-back portions 100, which extendparallel to the longitudinal axis 72 over the entire length of thecoupling element 92. They are dimensioned and sized such that they inturn abut the edges 126 of the insert 54.

The coupling element main body 94 has a width which corresponds to aclearance between the two wall portions 44, such that the couplingelement 72 may be inserted into the connection element receptacle 42.

The coupling members 96 abut the wall portions at concavely curved sidefaces 130 facing away therefrom, these side faces facing substantiallyin the direction of the intermediate portion 74 when the couplingelement 92 has been inserted. The coupling members 96 are conformed inshape to the side faces 130, such that flat contact between the couplingelement 92 and the side faces 130 is possible. The side faces 130 thusform a limit stop for the connection element 14 b, such that it can onlybe moved so far parallel to the longitudinal axis 72 in the direction ofthe bone screw 16 before the coupling members 96 strike against the sidefaces 130. Rotation of the coupling element 92 in the connection elementreceptacle 42 is not possible. Overall, the coupling element 92 definesa preferential direction 116 which extends transversely of thelongitudinal axis 72.

FIGS. 20 to 25 are schematic representations of a fourth exemplaryembodiment of a connection element designated overall with the referencesign 14 c. It differs in structure from the connection element 14 in thecoupling element 92 forming a second end. The coupling element 92 has asubstantially cuboidal coupling element main body 94, which comprisestwo coupling members 96 in the form of coupling projections 102, whichprotrude laterally on the coupling element main body 94 transversely ofthe longitudinal axis 72. The coupling members 96 define a diameterwhich corresponds to an internal diameter of the internal thread 46.

Each of the coupling members 96 is adjoined both on a side facing theintermediate portion 74 and on a side remote therefrom by two couplingmembers 97, which likewise take the form of coupling projections. Theseproject a little further from the coupling element main body 94 than thecoupling members 96. Furthermore they have an external contour which isconformed to the concave side faces 130 of the wall portions 44. In thisway, the coupling element 92, as is readily visible for example in FIG.22, may be inserted in a substantially positive-locking manner fromabove into the connection element receptacle 42.

The top 118 of the coupling element 92 is planar and forms a clampingsurface portion 122 for the distal end 124 of the fixing screw 50.

The coupling element 92 further has a connection element contact face134 for application against a further connection element, for example inthe form of a connecting rod 132, which is elongate and takes the formof a circular cylinder. The connection element contact face 134 takesthe form of a hollow-cylindrical wall face 136, against which an outerface 138 of the connecting rod 132 may be flatly applied. Facing awayfrom the intermediate portion 74 in the direction of the couplingelement 92 is a striking surface 140, against which an end face 142 ofthe connecting rod 132 may strike.

The particular configuration of the coupling element 92 allows this tobe fixed on the bone screw 16 together with the connecting rod 132. Theconnecting rod 132 is then held clamped between the coupling element 92and the insert 54, the coupling element 92 is between the connecting rod132 and the fixing screw 50.

FIGS. 26 to 30 are schematic representations of a fifth exemplaryembodiment of a connection element designated overall with the referencesign 14 d. It differs in structure from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element 92 in turn has a cuboidal main body with an endface 108 facing away from the intermediate portion 74 and inclinedrelative to the longitudinal axis 72. The top 118 of the couplingelement 92 is planar and forms a clamping surface portion 122 for thedistal end 124 of the fixing screw 50.

Main body side faces 144 extending substantially parallel to thelongitudinal axis 72 are curved at the point of transition to the bottom128 and form coupling members 98 in the form of set-back portions 100.The curvature of the coupling members 98 corresponds to an internaldiameter defined by the contact surface 64 of the insert 54, such thatthe coupling members 98 abut substantially flatly against the contactsurface 64. This is readily visible for example from FIG. 28.

A further coupling member 99 protrudes from the bottom 128 transverselyof the longitudinal axis 72 and defines a preferential direction 116.The coupling member 99 takes the form of a coupling projection 103 andhas the shape of a cone extending away from the bottom 128. The cone isdimensioned such that it may be introduced into the bore 68 of theinsert 54.

Through the particular configuration of the coupling element 92, thismay be secured to the bone screw 16 both parallel to the longitudinalaxis 72 and against rotation about the same.

FIGS. 31 to 34 are schematic representations of a sixth exemplaryembodiment of a connection element designated overall with the referencesign 14 e. It differs in structure from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element 92 has a substantially cuboidal coupling elementmain body 94 with two laterally projecting coupling members 96. Theseare convexly curved away from the coupling element main body 94 anddefine a diameter which corresponds to an internal diameter of theinternal thread 46.

Facing away from the intermediate portion 74, a coupling member 97 inthe form of a further coupling projection in each case adjoins thecoupling members 96. The coupling members 97 have an outer contour, suchthat they may be applied at least in places substantially flatly againstthe side faces 130 of the wall portions 44.

On the proximal side, further coupling projections 99 adjoin thecoupling members 96, said further coupling projections substantiallytaking the form of the coupling projections 96 of the connection element14 b. The coupling members 96 have an outer contour, which at least inpart allows a flat contact against the side faces 130 of the wallportions 44.

The top 118 of the coupling element 92 forms a planar clamping surfaceportion 122 for the distal end 124 of the fixing screw 50. The bottom128 of the coupling element 92 is formed by three coupling element mainbody side faces 146, 147 and 148 inclined relative to one another. Thecoupling element main body side face 147 extends parallel to the top 148and substantially in the region of the coupling members 96. The couplingelement main body side face 148 is inclined relative to the couplingelement main body side face 147 and forms an obtuse angle with thelatter. The coupling element main body side face 148 extendssubstantially in the region of the coupling members 97.

The coupling element main body side face 146 extends substantially inthe region of the coupling members 99 and forms an obtuse angle with thecoupling element main body side face 147. Overall, the three couplingelement main body side faces 146, 147 and 148 together form asubstantially concavely curved bottom 128 of the coupling element 92.

The coupling element 92 defines a preferential direction 116 whichextends transversely of the longitudinal axis 72.

The configuration of the coupling element 92 allows the connectionelement 14 e to be secured to the bone screw 16 with the fixing screw 50both parallel to the longitudinal axis 72 and against rotation aboutthis.

FIGS. 35 to 38 are schematic representations of a seventh exemplaryembodiment of a connection element designated overall with the referencesign 14 f. It differs from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element main body 94 is substantially cuboidal and has atits bottom 128 two coupling members 98 in the form of set-back portions100 extending parallel to the longitudinal axis, such that the couplingelement 92 may be applied with the set-back portions 100 against theedges 126 of the insert 54. The width of the main body correspondssubstantially to an inside width between the wall portions 44.

A coupling member 99 protrudes from the bottom 128 transversely of thelongitudinal axis 72, said coupling member being substantiallycylindrical and defining an external diameter which corresponds to aninternal diameter of the bore 68 of the insert 54. An end 150 of thecoupling member 99 facing away from the coupling element main body 94takes the form of a hemisphere 152.

The coupling element 92 thus defines a preferential direction 116 andallows the connection element 14 f to be secured to the bone screw 16 bymeans of the fixing screw 50 in a direction parallel to the longitudinalaxis 72 and against rotation about the longitudinal axis 72.

FIGS. 39 and 40 are schematic representations of an eighth exemplaryembodiment of a connection element designated overall with referencesign 14 g. It differs from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element 92 has a substantially cuboidal main body 94, withtwo coupling members 98 extending parallel to the longitudinal axis 72and taking the form of set-back portions 100. The top 118 of thecoupling element 92 forms a planar clamping surface portion 122 for thedistal end 124 of the fixing screw 50.

A coupling member 99 in the form of a cone with truncated pointprotrudes from the bottom 128 of the coupling element main body 94. Thecoupling member 99 is dimensioned such that it may be introduced inparticular into the bore 68 in the insert 54.

The coupling element 92 defines a preferential direction 116 and allowsthe connection element 14 g to be fixed to a bone screw 16 with thefixing screw 50 both parallel to the longitudinal axis 72 and againstrotation about the longitudinal axis 72.

FIGS. 41 to 45 are schematic representations of a ninth exemplaryembodiment of a connection element designated overall with the referencesign 14 h. This differs in structure from the connection element 14 inthe configuration of the coupling element 92.

The coupling element 92 corresponds in structure substantially to thecoupling element 92 of the connection element 14 c. It likewisecomprises coupling members 96 and 97 and has a top 118 which forms aplanar clamping surface portion 122. The bottom 128 of the couplingelement 92 is likewise planar. However, unlike with coupling element 92of the connection element 14 c, with the connection element 14 hcoupling members 98 extending parallel to the longitudinal axis 72 takethe form of set-back portions 100, which are arranged and dimensionedsuch that they abut the edges 126 of the insert 54 when the couplingelement 92 engages in the connection element receptacle 42.

The coupling element 92 defines a preferential direction 116 and may besecured with the fixing screw 50 in the connection element receptacle 42both against movement parallel to the longitudinal axis 72 and againstrotation about the longitudinal axis 72.

FIGS. 46 to 48 are schematic representations of a tenth exemplaryembodiment of a connection element designated overall with the referencesign 14 i. It differs from the connection element 14 in theconfiguration of the coupling element 92. The coupling element 92 isconfigured substantially identically to the coupling element 92 of theconnection element 14 d. It differs therefrom in that side faces 114 ofthe coupling element main body facing away from one another bear twocoupling members 96 protruding diametrically away from one another andtaking the form of coupling projections 102. The coupling members 96define an external diameter which corresponds to an internal diameter ofthe internal thread 46. The coupling element 92 of the connectionelement 14 i may thus be inserted in similar manner to the connectionelement 14 d into the connection element receptacle 42, wherein inaddition the coupling members 96 assist the conical coupling member 99protruding from the bottom 128 in preventing movement of the connectionelement 14 i relative to the bone screw 16 parallel to the longitudinalaxis 72.

The coupling member 92 of the connection element 14 i also defines apreferential direction 116, which extends transversely of thelongitudinal axis 72.

FIGS. 49 to 53 are schematic representations of two further exemplaryembodiments of connection elements designated overall with the referencesigns 14 j and 14 k respectively. They differ from the connectionelement 14 in the configuration of their coupling elements 92.

The coupling element 92 of the connection element 14 j is substantiallycuboidal and, like the coupling element 92 of the connection element 14a, has two coupling members 96 in the form of coupling projections 102protruding from the coupling element main body 94 in diametricallyopposed directions.

An end of the coupling element 92 facing away from the intermediateportion 74 takes the form of a cylindrical end face 108, so as to formoverall a planar cylindrical disc. The top 128 of the coupling element92 forms a planar surface portion 120. A coupling member 99 in the formof a substantially cylindrical coupling projection 103 protrudes fromthe bottom 128 transversely of the longitudinal axis 72, and the end ofsaid coupling projection facing away from the coupling element main body94 is spherically rounded. The external diameter of the coupling member99 is conformed to the internal diameter of the bore 68 of the insert54.

Furthermore, two coupling members 98 are formed on the coupling element92 which take the form of set-back portions 100, extend parallel to oneanother and extend as far as the end face 108. The set-back portions 100are dimensioned such that they may abut the edges 126 of the insert 54.

A coupling member 97 in the form of a coupling recess 154 is formed onthe top 118 of the coupling element 92. The coupling recess 154 ishollow-spherical in shape. It is arranged and formed substantiallycoaxially to the coupling member 99.

The top 118 furthermore forms a connection element contact face 134. Acorresponding connection element contact face 134 of the couplingelement 92 of the connection element 14 k may be applied thereto.

The coupling element 92 of the connection element 14 k has a planar top118, which forms a planar clamping surface portion 122 for the end 124of the fixing screw 50. The coupling element main body 94 issubstantially cuboidal and likewise has two coupling members 96projecting transversely of the longitudinal axis 72. These define acommon external diameter, which corresponds to an internal diameter ofthe internal thread 46.

In the direction away from the intermediate portion 74, coupling members97 in the form of coupling projections with a shape corresponding to theconcave side faces 130 of the wall portions 44 adjoin the couplingmembers 96.

A further coupling member 99 projects from the bottom 128 of thecoupling element 92 of the connection element 14 k, and has a shapecorresponding to the coupling recess 154, such that the coupling member99 may be introduced in positive-locking manner into the coupling recess154.

The two connection elements 14 j and 14 k may be fixed with their twocoupling elements 92 jointly in a connection element receptacle 42 of abone screw 16. First of all, the coupling element 92 of the connectionelement 14 j is inserted in the described manner into the connectionelement receptacle 42, such that the coupling member 99 protrudes intothe bore 68. Then the connection element 14 k may be inserted with itscoupling element 92 into the connection element receptacle 42, such thatthe coupling member 92 protrudes into the coupling recess 154.

With the fixing screw 50 the two connection elements 14 j and 14 k maybe fixed in jointly clamped manner to the bone screw 16. The particularconfiguration of the coupling elements 92 of the connection elements 14j and 14 k in practice allows simple extension of a connection element.

FIGS. 54 to 56 are schematic representations of a thirteenth and afourteenth exemplary embodiment of a connection element, designated withreference signs 14 l and 14 m. The connection elements 14 l and 14 mdiffer from the connection element 14 in the configuration of theircoupling elements 92.

The coupling element 92 of the connection element 14 l has asubstantially cuboidal main body. Two coupling members 96 in the form ofcoupling projections 102 protrude therefrom transversely of thelongitudinal axis 72 and facing in diametrically opposed directions.These are curved convexly away from the coupling element main body 94and together define an external diameter which corresponds to aninternal diameter of the internal thread 46.

On the bottom 128, parallel to the longitudinal axis 72, two couplingmembers 98 take the form of lateral set-back portions 100, which aredimensioned and arranged such that they may be placed onto the edges 126of the insert 54. The bottom 128 is planar. The top 118 is likewiseplanar and forms a connection element contact face 134 for applicationagainst the connection element 14 m. In addition, a coupling member 99in the form of a coupling projection protrudes from the top 118 in adirection transverse to the longitudinal axis 72. The coupling member 99is of substantially elongate, cuboidal construction with rounded endedges and slightly inclined side faces, so as to form overall a slightlyconical projection.

The coupling element 92 of the connection element 14 m has asubstantially cuboidal coupling element main body 94, away from whichtwo coupling members 96 in the form of coupling projections 102 extendtransversely of the longitudinal axis 72 in diametrically opposeddirections.

The coupling projections 102 are curved convexly away from the couplingelement main body 94 and together define common an external diameterwhich corresponds to an internal diameter of the internal thread 46.

The coupling members 96 are adjoined on their side facing away from theintermediate portion 74 by two coupling members 97 in the form ofcoupling projections, which have an outer contour conformed to the sidefaces 130 of the wall portions 44.

In addition, the coupling element 92 is provided with a coupling recess144 extending transversely of the longitudinal axis 72 and taking theform of a through opening 156. The through opening 156 substantiallytakes the shape of an elongate hole with rounded corners. Moreover, itis slightly conical, such that the coupling member 99 may be inserted inpositive-locking manner into the coupling recess 154.

The bottom 128 of the coupling element 92 of the connection element 14 mis planar, like the top 118. The top 118 forms a planar clamping surfaceportion 122 for the distal end 124 of the fixing screw 50.

Like the connection elements 14 j and 14 k, the connection elements 14 land 14 m may be coupled together and fixed jointly to a single bonescrew 16. To this end, first of all the coupling element 92 of theconnection element 14 l is inserted into the connection elementreceptacle 42, such that the coupling member 99 faces away from thefixing part 24. Then the coupling element 92 of the connection element14 m may be inserted into the connection element receptacle 42, suchthat the coupling recess 154 receives the coupling member 99. Finallythe coupling elements 92 may be fixed in clamped manner to the holdingpart.

FIGS. 57 to 61 are schematic representations of two further exemplaryembodiments of connection elements designated with the reference signs14 n and 14 o. They differ from the connection element 14 in theconfiguration of their coupling elements 92.

The connection element 14 n has a coupling element 92, which correspondssubstantially to the coupling element 92 of the connection element 14 h.It differs merely in the configuration of a coupling member 99 in theform of a coupling recess 154.

The coupling recess 154 extends from the end face 108 towards theintermediate portion 74, in such a way that its width decreases, suchthat overall an equal-sided prism is formed as a hollow. The couplingrecess 154 also extends from the top 118. In other words, the couplingrecess 154 opens away from the top 118 and from the end face 108.

The top 118 furthermore forms a planar clamping surface portion 122. Aboundary face 158 of the coupling recess 154 extending parallel to thebottom 128 forms a connection element contact face 134 for applicationagainst the connection element 14 o, specifically the coupling element92 thereof.

The coupling element 92 of the connection element 14 o has the shape ofan equal-sided prism and corresponds to the coupling recess 154. Thecoupling element 92 may thus be introduced completely into the couplingrecess 154, as illustrated schematically by way of example in FIG. 60.

The top 118 of the coupling element 92 of the connection element 14 ofurthermore forms a planar clamping surface portion 122. The bottom 128of the coupling element 92 abuts the boundary face 158.

The coupled-together coupling elements 92 of the connection elements 14n and 14 o together form a unit, which has the same shape as thecoupling element 92 of the connection element 14 h. Using the fixingscrew 50, the two connection elements 14 n and 14 o may be secured tothe bone screw 16 in a direction parallel to the longitudinal axis 72and against rotation about the same.

FIGS. 62 to 67 are schematic representations of a seventeenth exemplaryembodiment of a connection element designated overall with the referencesign 14 p. It differs from the connection element 14 in theconfiguration of the coupling element 92.

The coupling element 92 of the connection element 14 p corresponds instructure substantially to the coupling element 92 of the connectionelement 14 c. Two coupling members 96 protrude laterally from asubstantially cuboidal coupling element main body 94 in diametricallyopposing directions, which define a common external diameter conformedto an internal diameter of the internal thread 46.

The coupling members 97 protruding on either side of the couplingmembers 96 have an external contour which is in turn conformed to theconcave side faces 130 of the wall portions 44. The coupling members 97formed at the free end of the coupling element 92 additionally extendbeyond the top 118 and thereby enlarge the end face 108 of the couplingelement 92 in comparison with the end face 108 of the coupling element92 of the connection element 14 c. Overall, an end wall 160 is formed inthis way which has a side face 162 facing in the direction of theintermediate portion 74, which side face takes the form of ahollow-cylindrical wall portion. An internal diameter defined by theside face 162 is conformed to an external diameter of the externalthread 48 of the fixing screw 50.

The width of the end wall 160 corresponds substantially to the distancebetween the two wall portions 44, such that the end wall 160 closes theconnection element receptacle 42 in a direction facing away from theintermediate portion 44.

The coupling element 92 further comprises a further coupling member 99in the form of a coupling recess 154, which takes the form of a throughopening 156, specifically the form of an elongate hole. The throughopening connects the top 118 with the hollow-cylindrical connectionelement contact face 134, which is formed on the bottom 128 of thecoupling element 92. The through opening 156 allows the use of a fixingscrew 50, which is inserted conventionally, i.e. it does not comprise asubstantially planar distal end 124 but rather an end which tapers to apoint.

Like the connection element 14 c, the connection element 14 p, togetherwith an elongate, circular cylindrical connecting rod 132, allows fixingwith the fixing screw 50 in the connection element receptacle 42 of thebone screw 16. The connection element 14 p thus allows connecting rods132 to be extended simply and without further auxiliary means.

The above-described exemplary embodiments of connection elements may beproduced from biocompatible metals or plastics. They are preferably ofone-piece construction.

The coupling elements of the connection elements may be combined invirtually any desired way. They may optionally be arranged or formed onconnection elements with resilient intermediate portions 74 or indeed onnon-resilient or substantially non-resilient intermediate portions, forexample on circular cylindrical connecting rods. In particular it isalso conceivable for connection elements to have two coupling elements.These may be of identical or indeed different configuration.

Furthermore, the described coupling members may be combined with oneanother in principle in any desired manner for the coupling elements.For example, through openings may also be provided on coupling elementswhich were described above and did not have any through openings.

What is claimed is:
 1. A connection element for a spine stabilizationsystem, comprising: a first end for fixing to a first bone fixationdevice, a second end for fixing to a second bone fixation device, and anintermediate portion arranged or formed between the first and secondends and defining a longitudinal axis, wherein: at least one of thefirst and second ends takes the form of a coupling element for fixingthe connection element to a bone fixation device in at least one definedorientation relative to the longitudinal axis, the coupling element hasa shape other than a circular cylinder; the coupling element comprises acoupling element main body having a planar bottom side and at least onecoupling member arranged or formed on the coupling element main body,and the at least one coupling member extends parallel to thelongitudinal axis and comprises set-back portions on the bottom sidethereof, the set-back portions having one side face each which extendsparallel to the bottom side.
 2. The connection element according toclaim 1, wherein at least one of: the first and second ends take theform of a coupling element having a shape other than a circularcylinder, the coupling element is of a one-piece construction, and theconnection element is of a one-piece construction.
 3. The connectionelement according to claim 1, wherein: the at least one coupling memberextends in a coupling member direction which extends parallel to ortransversely of the longitudinal axis.
 4. The connection elementaccording to claim 1, wherein: the coupling element main body takes theform of a straight or oblique general cylinder, and a cylinderlongitudinal axis defined by the cylinder extends transversely of thelongitudinal axis.
 5. The connection element according to claim 1,wherein: the at least one coupling member comprises a couplingprojection or a coupling receptacle.
 6. The connection element accordingto claim 1, wherein at least one of: the coupling element ismirror-symmetrical relative to a mirror plane containing thelongitudinal axis, a center of gravity of the coupling element is spacedfrom the longitudinal axis, and an end face of the coupling elementfacing away from the intermediate portion is inclined relative to thelongitudinal axis or rounded.
 7. The connection element according toclaim 1, wherein: the coupling element comprises a connection elementcontact face for application against a further connection element, inparticular against an end of the further connection element.
 8. Theconnection element according to claim 7, wherein at least one of: theconnection element contact face at least in part takes the form of ahollow-cylindrical wall face, and the connection element contact face atleast in part takes the form of a planar contact face portion.
 9. Theconnection element according to claim 1, wherein the intermediateportion is a winding leaf spring element in the form of a strip andcomprises at least one recess open laterally in a recess directiontransverse to the longitudinal axis.
 10. The connection elementaccording to claim 1, wherein the connection element is made from ametallic material or a plastics material.
 11. The connection elementaccording to claim 1, wherein the intermediate portion is at least inpart flexible.
 12. The connection element according to claim 1, wherein:the at least one coupling member comprises coupling projections whichprotrude laterally from the coupling element main body transversely tothe longitudinal axis.
 13. The connection element according to claim 1,wherein the coupling element comprises a top which forms a planarclamping surface portion.
 14. The connection element according to claim1, wherein: the coupling element comprises a top which forms a planarclamping surface portion.
 15. A spine stabilization system, comprising:at least one first bone fixation device, at least one second bonefixation device, and at least one connection element, the at least oneconnection element comprising: a first end for fixing to the at leastone first bone fixation device, a second end for fixing to the at leastone second bone fixation device, and an intermediate portion arranged orformed between the first and second ends and defining a longitudinalaxis, wherein: at least one of the first and second ends takes the formof a coupling element for fixing the connection element to the at leastone first of the at least one second bone fixation device in at leastone defined orientation relative to the longitudinal axis, the couplingelement has a shape other than a circular cylinder, the coupling elementcomprises a coupling element main body having a planar bottom side andat least one coupling member arranged or formed on the coupling elementmain body, and the at least one coupling member extends parallel to thelongitudinal axis and comprises set-back portions on the bottom sidethereof, the set-back portions having one side face each which extendsparallel to the bottom side.
 16. The spine stabilization systemaccording to claim 15, wherein: the at least one coupling membercomprises coupling projections which protrude laterally from thecoupling element main body transversely to the longitudinal axis. 17.The spine stabilization system according to claim 15, wherein thecoupling element comprises a top forming a planar clamping surfaceportion.
 18. The spine stabilization system according to claim 15,wherein: the coupling element comprises a top forming a planar clampingsurface portion.
 19. A connection element for a spine stabilizationsystem, comprising: a first end for fixing to a first bone fixationdevice, a second end for fixing to a second bone fixation device, and anintermediate portion arranged or formed between the first and secondends and defining a longitudinal axis, wherein: at least one of thefirst and second ends takes the form of a coupling element for fixingthe connection element to a bone fixation device in at least one definedorientation relative to the longitudinal axis, and the coupling elementhas a shape other than a circular cylinder, the coupling elementcomprises a coupling element main body and first coupling members in theform of coupling projections arranged or formed on each side of thecoupling element main body, which first coupling members protrudelaterally from the coupling element main body transversely to thelongitudinal axis, and each of the first coupling members is adjoinedboth on a side facing the intermediate portion and on a side remotetherefrom by two second coupling members, which likewise take the formof coupling projections.
 20. A spine stabilization system, comprising:at least one first bone fixation device, at least one second bonefixation device, and at least one connection element, the at least oneconnection element comprising: a first end for fixing to the at leastone first bone fixation device, a second end for fixing to the at leastone second bone fixation device, and an intermediate portion arranged orformed between the first and second ends and defining a longitudinalaxis, wherein: at least one of the first and second ends takes the formof a coupling element for fixing the connection element to a bonefixation device in at least one defined orientation relative to thelongitudinal axis, and the coupling element has a shape other than acircular cylinder, the coupling element comprises a coupling elementmain body and first coupling members in the form of coupling projectionsarranged or formed on each side of the coupling element main body, whichfirst coupling members protrude laterally from the coupling element mainbody transversely to the longitudinal axis, and each of the firstcoupling members is adjoined both on a side facing the intermediateportion and on a side remote therefrom by two second coupling members,which likewise take the form of coupling projections.